Two-stage water heater assembly

ABSTRACT

A two stage water heater assembly comprising a tankless stage, which preheats water, and water storage tank stage, which stores the preheated water and maintains the water at a desire temperature. This water heater assembly provides the user with an unlimited supply of hot water on demand while doing so in a more energy efficient manner than either an inline tankless water heater or a traditional tank-type water heater.

FIELD OF THE INVENTION

The invention relates to a dual stage water heater assembly whichcombines the advantages of a tankless water heater and a moretraditional tank-type water heater.

BACKGROUND OF THE INVENTION

Tankless inline water heaters are designed to heat a continuous supplyof water on demand of the user. They accomplish this in severaldifferent ways. In the most common embodiment, the water travels acircuitous route past a heating element or elements, which heat thewater to a desired temperature. Tankless inline water heaters are morefuel efficient than traditional tank water heaters. One disadvantage ofthis type of system, however, is that in many cases it cannot keep upwith demand, with the result that water of an undesirably lowtemperature is encountered. The size of the heating element or elementsin a tankless water heater limits the amount of hot water that can beprovided at one time. Without a large heating element, a tankless waterheater can only provide hot water to one or two users. In addition, theheating element or elements in a tankless water heater only beginheating the water when the hot water is demanded. In a tankless waterheater, small demands, unintended to call for hot water, can activatethe heating element or elements unless a delay mechanism is used. Use ofa delay mechanism, however, substantially lengthens the response timewhen hot water is actually desired. During cold weather, cooler waterentering a tankless water heater may not be heated quickly enough or hotenough for the intended use, resulting in a cold shower or other suchinconvenience.

Traditional tank-type water heaters are able to provide water on demand,as hot as the user may desire. But, in order to provide hot water ondemand, a large amount of energy must be used to heat and maintain thewater in the tank at a desired temperature. A tank water heater also islimited in the amount of hot water it can supply. If a number of usersdesire hot water at the same time, a tank water heater may quickly runout of its available supply of hot water, unless a larger tank,requiring more energy, is utilized.

SUMMARY OF THE INVENTION

To solve the problems with existing inline tankless water heaters andtraditional tank-type water heaters, I have designed an improved twostage water heater assembly. The invention comprises a tankless inlinewater heater stage and a traditional tank-type water heater stage in away that provides the user with unlimited hot water on demand and withenergy savings because a much smaller tank can be used with the tankwater heater stage.

Water is heated in the tankless stage and enters the tank stage at atemperature at or near the temperature selected by the user. As aresult, the tank is smaller and requires less energy to maintain thewater at a desired temperature. Consequently, a virtually unlimitedsupply of water can be provided at a desired high temperature by using amodest amount of energy and smaller tank in the tank stage.

In addition, the present invention can be easily retrofitted into anexisting home because it takes up about the same amount of space as atraditional tank-type water heater. Because installation of the presentinvention does not require extensive modification of an existing home,it is much less expensive to install than existing two stage waterheaters. As such, the present invention provides an inexpensive meansfor increasing energy savings by reducing the amount of energy that isneeded to heat water in a residential or commercial setting.

In one aspect of this invention, it provides a hot water heater assemblywherein the desirable features of tankless inline water heater arecombined with the desirable features of a traditional tank-type waterheater, commonly used in the United Sates.

In another aspect of this invention, it provides an improved hot waterheater assembly, which provides an unlimited supply of hot water ondemand while using less energy and can be installed inexpensively in anexisting home.

To the accomplishment of the above and related aspects, the inventionmay be embodied in the form illustrated in the accompanying drawings.The drawings, however, are illustrative only. Variations arecontemplated as being part of the invention, limited only by the scopeof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the apparatus of the invention.

FIG. 2 is a perspective view of the apparatus of the invention.

FIG. 3 is a top view of the tankless stage of the apparatus of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a two stage water heater assembly 1, comprising atankless stage 2 and a storage stage 3. Water 4 enters the tanklessstage through cold water inlet 5. The water 4 circulates throughentrance chamber 6 through coiled tubing 7 and is heated by a firstheating means 8. In FIG. 1, a natural gas burner is used as the heatingmeans although the heating means could also include a propane burner, aheating oil burner or electric heating elements. Heating means 8 isconnected to control valve 9. Exhaust gas from heating means 8 is ventedto the atmosphere through exhaust flue 24. After being heated by heatingmeans 8, pre-heated water 14 exits tankless stage 2 through hot wateroutlet 10. Pre-heated water 14 then enters storage stage 3 through hotwater inlet port 11, which is connected to flow control valve 12.Pre-heated water 14 is stored in water storage tank 13 until it isdesired for use. Pre-heated water 14 is maintained at a desiredtemperature by second heating means 15, which is located beneath lowerwall 17 and connected to control valve 16. Exhaust from heating means 15is vented to the atmosphere through exhaust flue 18. Heated water 19exits storage stage 3 for use by the user through hot water outlet 20,which is activated by hot water flow control valve 21. Temperaturesensing means 22 and tank water level sensing means 23 are locatedwithin storage tank 13. Temperature sensing means 22 is connected tocontrol valve 16, which activates heating means 15 when temperaturesensing means 22 indicates that the temperature of pre-heated water 14in storage tank 13 is below a temperature selected by the user. Tankwater level sensing means 23 is connected to flow control valve 12,which activates hot water inlet port 11 when tank water level sensingmeans 23 indicates that pre-heated water 14 has dropped below a certainlevel within storage tank 13. Flow control valve 12 is connected tocontrol valve 9. When flow control valve 12 activates hot water inletport 11, it also sends a signal to control valve 9, which in turnactivates heating means 8, which heats water 4 flowing through coiledtubing 7.

When the user desires hot water and turns on a hot water tap, controlvalve 21 is activated and opens hot water outlet 20 permitting hot water19 to flow through pipes to the user. This will result in a drop in thewater level within storage tank 13 causing tank water level sensingmeans 23 to send a signal to flow control valve 12, which then permitspre-heated water 14 to enter storage tank 13 through hot water inletport 11.

The assembly is approximately the same size as traditional tank-typewater heater, which is predominantly used in the U.S., so it can easilyfit into the space that was previously occupied by a traditionaltank-type water heater. Thus, it provides a cheaper, more efficient,more reliable option to either an inline tankless water heater or atraditional tank-type water heater.

The description of the invention above should not be interpreted aslimiting the invention to the disclosed embodiment because those who areskilled in the art to which the invention relates will be able to deviseother equivalent forms thereof within the scope of the invention.Variations and changes, which are obvious to one skilled in the art, areintended to be within the scope and nature of the present invention.

1. A two-stage water heater assembly comprising: a tankless stagecomprising an entrance chamber with an elongated, coiled tube locatedwithin said entrance chamber, said tube connected in fluid receivingrelation to a cold water inlet and located above first heating means,said first heating means are adapted for heating water that flowsthrough said tube, said water being allowed to exit the tankless stagethrough a hot water outlet; a storage stage comprising an uprightthermally insulated cylindrical water storage tank with a hot waterinlet port connected in fluid receiving relation to the hot water outletof said tankless stage and attached to a flow control valve, secondheating means for heating the water within the storage tank, temperaturesensing means for said water storage tank, said temperature sensingmeans producing a signal indicative of the water temperature in saidwater storage tank, tank water level sensing means, said tank waterlevel sensing means producing a signal indicative of the water level insaid water storage tank, said water being allowed to exit the storagestage through a second hot water outlet; and control means connected tosaid flow control valve and responsive to the signals produced by saidtank water level sensing means to maintain the water stored in the waterstorage tank at a certain level by activating the hot water inlet portonly if the tank water level sensing means indicate that the water isbelow the required water level; and control means connected to saidsecond heating means and responsive to the signals produced by saidtemperature sensing means to maintain the water stored in the waterstorage tank and released through said second hot water outlet at adesired temperature by activating the heating element in the storagestage only if the water temperature sensing means indicate that thewater is below the desired outlet temperature as selected by an outlettemperature selecting means.
 2. The two stage water heater assembly ofclaim 1 wherein the heating means is electrical.
 3. The two stage waterheater assembly of claim 1 wherein the heating means is natural gas.